/Engine/Source/Runtime/HeadMountedDisplay/Public/IHeadMountedDisplay.h
Called just before rendering the current frame on the render thread. Invoked before applying late update, so plugins that want to refresh poses on the render thread prior to late update. Use this to perform any initializations prior to rendering.
virtual void BeginRendering_RenderThread ( const FTransform & NewRelativeTransform, [FRHICommandListImmediate](API\Runtime\RHI\FRHICommandListImmediate) & RHICmdList, [FSceneViewFamily](API\Runtime\Engine\FSceneViewFamily) & ViewFamily )